1. Field of the Invention
This invention relates to a flue control device and more particularly to a non-restrictive flue control device wherein a baffle mechanism having flanges extending in an upstream direction disrupt the smooth flow of gases as well as change the direction of flow of the gases in order to slow the flow of gases through the exhaust stack.
2. Description of Prior Art
In a gas furnace, heated combustion gases warm the air being circulated throughout the building and then are exhausted through an exhaust stack or flue. A cause of inefficiency in such a system is the discharge of combustion gases at too fast a rate, before the combustion gases have had a chance to transfer a maximum amount of their heat to the air being circulated throughout the rooms. The rate at which combustion gases are exhausted is dependent upon a number of factors, one of which is the diameter of the exhaust stack. Other factors are dependent on the nature of the dwelling, conditions external to the dwelling, and a number of other individual factors, such that the rate of gas exhaust can vary widely among different houses, even though the houses may have the same type of heating system.
Various types of devices have been developed in order to improve heating efficiency by slowing the rate at which combustion gases are exhausted through an exhaust stack. One type of device is a flue restricting device, which essentially is a baffle that restricts or narrows the cross-sectional area of the exhaust flue. Such a device generally is movable to restrict the flue only when the furnace is not operating and to open fully when the furnace is operating. This type of device thus has no effect on furnace operation during the time of greatest heat loss. A flue restricter that restricts the area of the exhaust flue during normal operation can be in violation of applicable fire codes.
Another type of device for slowing the flow of exhaust gases during normal furnace operation employs a baffle mechanism adjacent an enlarged baffle chamber in the exhaust stack. The baffle mechanism causes a change in direction of the gases as they flow around the baffle but the enlarged chamber prevents actual constriction of the flue size. This is called a non-restrictive flue control device.
These devices cause some retardation of the gas flow rate due to the change in linear direction of the gases. However, gases also swirl in a circular pattern as they flow and a simple flat baffle does little to disrupt this swirling action. To impede the swirling action, some nonrestriction devices have incorporated small lips on the baffle, but the performance is still less than desirable.
An object of the present invention is to provide a simple and yet effective flue control device that changes the longitudinal direction of the gases and disrupts the swirling pattern of gas flow in a manner that maximizes the retardation of gas flow in widely varying conditions without creating dangerous exhaust flow conditions.
Another object of the present invention is to provide a flue control device of this nature that is safe and effective and inexpensive to construct yet can be modified to accommodate differing flue conditions and differing installations.